This invention relates to fluid mixtures and more particularly to a method and device for mixing fluids to obtain a known concentration whereby instrumentation for measuring fluid concentrations may be calibrated.
Present day concern for the quality of environmental atmospheres requires accurate sophisticated analytical instrumentation for the detection and monitoring of specific contaminants. This is especially true in confined areas such as those of a submarine, diving habitats, spacecraft, or other such confined areas. Proposed requirements of atmospheric contaminant measurements have extended in some instances beyond the capability of current measuring instrumentation. Therefore new analytical concepts and instrumentation must be developed to cope with the present needs. One major problem exists, however, in that instrumentation cannot be evaluated for accuracy and low concentrations of gases unless there is a suitable instrument to accurately form the low concentrations desired for calibration.
A conventional method of producing a dynamic gas stream containing a very low concentration of another gaseous substance involves a series of successive blendings of separate gas streams at different flow rates. Several stages may be required and the flow rate of each stage of dilution must be accurately controlled. This method is not satisfactory where very low concentrations (parts per billion or less) are required, because of the difficulty of adjusting and maintaining accurate gas flows. In this type of prior art, an adjustment or change in flow rate at any one stage upsets the flow rate at all other stages. Further, such instruments are large, fragile and contain considerable interconnecting tubing.